1. Field of the Invention
This invention relates to contents a content delivery apparatus which performs a delivery service of a content such as a video via a communication line to a terminal device on a user side, a user terminal device which receives the delivery service, a relief management method to relieve an impossibility of viewing when a failure occurs and a computer program which achieves the management method. More specifically, the present invention relates to a relief technique for a failure occurrence period within a period when a validity term is set to the content.
2. Description of the Related Art
A download type video content delivery service using a network such as a broadband encrypts the content with a specified encryption key to deliver it to a user terminal device of a request source and delivers the encryption key in response to a view request within a view period. The delivery service then makes it possible for the encrypted content to be decrypted and reproduced on a user terminal side. In such a system, the following cases or cases of combinations thereof are mainly utilized as view service forms:
a service in which a user can view contents as many as it wants within a fixed time period (for example one month) and in a prescribed range;
a service in which the user pay charges at every time when it selects contents to be viewed;
a service in which the user specifies the number of times of viewing and can view the contents by the specified times;
a service in which the user pays prescribed charges at every time when it views the contents; and
a service in which the user specifies a time period and can view any number of times within the time period.
The service forms described above can be classified into two forms of a type which limits the number of times of the viewing and a type which permits the viewing by specifying the time period.
By the way, in the above-mentioned system to provide a content delivery as a service, it is preferable to provide compensation to the user in a certain form by taking into a consideration the case, in which a failure occurs in the system or the network (hereinafter, this compensation is referred to as user relief).
A conventional user relief method generally gets, in advance by a contract, an agreement that a service provider is dispensed a responsibility for the user in the case in which the failure occurs in the system or network.
However, a viewing service with a time limit causes a problem when the failure occurs in a time band desired by the user. That is, in such a case, although the user has any self-responsibility, the user tends to miss a viewing chance. And when the user cannot have a time to view the contents within the view period, the user complains extremely, so that the case may cause a trouble between the service provider and user. As like this case, when the user cannot receive an expected service, the service provider bears extra costs and burdens to offer apologies for every user so as to avoid dissatisfaction of the user and a loss of a belief of the service provider. This problem is caused from an insufficient relief method for the user, as a content of a service, and it is required for the problem to be solved quickly.
Jpn. Pat. Appln. KOKAI Publication No. 2004-350150 discloses the detailed contents of such a content delivery apparatus and a way of operations of its user terminal device.
Further, an invention regarding a relief method when a viewing quality is deteriorated in a content delivery system is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2004-343238. This delivery system however delivers content in a streaming type and relieves the content in accordance with a situation of deterioration in viewing quality, so that a viewing procedure is quite different from that of the delivery system of the present invention in which the encrypted content is downloaded and the encryption key is required for viewing it.